If a woman makes a mistake about when she becomes pure following menstruation, is she sinning?

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Check below answers in case you are looking for other related questions:
She is confused about purity following menses; what should she do?
The discharge which is passed continuously by a woman does not have any effect on the fast

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She is confused about purity following menses; what should she do?
The discharge which is passed continuously by a woman does not have any effect on the fast

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